What is claimed is the ornamental design for a head cover, as shown and described.
FIG. 1 is a perspective view of a head cover, showing the new design;
FIG. 2 is a front elevational view thereof;
FIG. 3 is a rear elevational view thereof;
FIG. 4 is a right-side elevational view thereof, the left-side elevational view being a mirror image thereof;
FIG. 5 is a top plan view thereof; and,
FIG. 6 is a bottom plan view thereof.
The broken lines showing a person's head in FIG. 1 are included for the purpose of illustrating the invention in use, and form no part of the claimed design. The broken lines occurring on the surfaces of the claimed design are stitching and form a part of the claimed design.